Use of Soil Solarization to Control Fusarium Wilt of Watermelon. R. D. Martyn, Associate Professor, Department of Plant Pathology and Microbiology, Texas Agricultural Experiment Station, College Station 77843. T. K. Hartz, Extension Vegetable Specialist, Texas Agricultural Extension Service, Weslaco 78596. Plant Dis. 70:762-766. Accepted for publication 11 March 1986. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/PD-70-762.

Soil solarization for either 30 or 60 days was effective in delaying the onset of wilt symptoms as well as in reducing total disease incidence in a Fusarium-susceptible watermelon cultivar, Sugarbaby, but complete disease control was not achieved. These effects lasted over two growing seasons; however, best control was obtained during the first year. Temperature maxima during 17–19 July 1984 in solarized soil were 60, 50, 42, and 37 C at depths of 2, 10, 20, and 30 cm, respectively. The population of Fusarium oxysporum f. sp. niveum was reduced dramatically throughout the soil profile after 30 days of solarization compared with a similarly infested, nonsolarized treatment. Further decline in F. o. f. sp. niveum was achieved in the top 10 cm of soil after the 60-day solarization. Populations of saprophytic Fusarium spp. were twofold higher at 15–20 cm deep and eightfold higher at 30–35 cm deep after 30 days of solarized than in nonsolarized soil.